/*
Given a binary tree, return the inorder traversal of its nodes' values.

For example:
Given binary tree {1,#,2,3},
   1
    \
     2
    /
   3
return [1,3,2].

Note: Recursive solution is trivial, could you do it iteratively?
*/

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    vector<int> inorderTraversal(TreeNode *root) {
        vector<int> results;
        if (!root) return results;
        TreeNode *cur = root;
        while (cur) {
            if (cur->left) {
                TreeNode *next = cur->left;
                // make cur the right child of the 
                // rightmost node in left subtree
                {
                    TreeNode *n = next;
                    while (n->right) n = n->right;
                    n->right = cur;
                }
                cur->left = NULL;
                cur = next;
            } else {
                results.push_back(cur->val);
                cur = cur->right;
            }
        }
        return results;
    }
};
